Not all of the parts I used here are necessarily required. For example, you could use a resonator instead of a crystal, or hypothetically neither. But I won't be going into detail about alterations, if you change something I'll assume you know what your doing. If you don't know what you are doing, you might want to stick to what I've outlined here until you are a little more comfortable with AVR's.
In this project I used an ATtiny25 microcontroller
, a handy little chip. I picked this one for this project because it's small and has 2 timers, which will make the programming easy. In order to complete this project you'll need a programmer, there are lots of methods on the internet for programming AVR's (look up "AVR programming" on instructables or google). I personally use the USBtinyISP that Ladyada sells
Except for the AVR you can proabaly scalvange most of this stuff from old electronics. I needed to make an order to Digi-Key
anyway, so I just got this stuff there.
What you need:
*I used a 3.6 V lithium battery, you can use something else, just as long as the voltage is between 3 and 5.5 volts (the weaker the battery, the more quiet the speaker will be).
**You don't need the IC socket, but it will make it very difficult to reprogram the AVR afterwards if you don't use one.